Traits, Genes, and Alleles 6.3 6.4

TERMINOLOGY FOR THE SUCCESS OF GENETICS

FATHER OF GENETICS

Term: TRAIT

• Biological factor being studied.

• Example: A blood disease like hemophilia or bleeder’s disease!

Term: DOMINANCE:

• THE PREDOMINANT FORM OF A GIVEN TRAIT.

• Example: Brown eyes are dominant to blue eyes.

Term: RECESSIVE

• A form of a trait not expressed frequently.

• Example: Being left handed!

Term: Gene

• A DNA unit of heredity located on a chromosome that controls traits!

• Example: Look at the “Human Genome” chart on the side board that shows genes for given characteristics!

Term: ALLELE

• A gene for a given trait:

• Examples:

• A

• B or

• O for blood types

Term: HYBRID

• A condition resulting from the cross of two, pure, contrasting traits of a given characteristic such as eye color.

Example:

BB x bb

Bb = Hybrid!

Term: PHENOTYPE

• Physical appearance of a given characteristic.

Example: Type A blood

Eye color - Brown or blue

Right or left handed

Term: GENOTYPE

• The allele expression of a given characteristic.

• Example: BB, Bb, or bb.

• BB - HOMOZYGOUS DOMINANT

• bb - HOMOZYGOUS RECESSIVE

• Bb - HETEROZYGOUS

Quiz

• XX• tt• Yy• zz• Oo• TT• AA• jj

• Tt• Bb• Ii• Kk• Nn• NN• Nn• rr